From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: [PATCH v4 3/3] net: igmp: Allow user-space configuration of igmp unsolicited report interval Date: Wed, 7 Aug 2013 03:00:41 +0200 Message-ID: <20130807010041.GG16410@order.stressinduktion.org> References: <20130731063442.GA10498@order.stressinduktion.org> <1375812195-6575-1-git-send-email-william.manley@youview.com> <1375812195-6575-4-git-send-email-william.manley@youview.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: netdev@vger.kernel.org, bcrl@kvack.org, luky-37@hotmail.com, sergei.shtylyov@cogentembedded.com, bhutchings@solarflare.com, davem@davemloft.net To: William Manley Return-path: Received: from order.stressinduktion.org ([87.106.68.36]:35877 "EHLO order.stressinduktion.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754515Ab3HGBAm (ORCPT ); Tue, 6 Aug 2013 21:00:42 -0400 Content-Disposition: inline In-Reply-To: <1375812195-6575-4-git-send-email-william.manley@youview.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Aug 06, 2013 at 07:03:15PM +0100, William Manley wrote: > Adds the new procfs knobs: > > /proc/sys/net/ipv4/conf/*/igmpv2_unsolicited_report_interval > /proc/sys/net/ipv4/conf/*/igmpv3_unsolicited_report_interval > > Which will allow userspace configuration of the IGMP unsolicited report > interval (see below) in milliseconds. The defaults are 10000ms for IGMPv2 > and 1000ms for IGMPv3 in accordance with RFC2236 and RFC3376. > > Background: > > If an IGMP join packet is lost you will not receive data sent to the > multicast group so if no data arrives from that multicast group in a > period of time after the IGMP join a second IGMP join will be sent. The > delay between joins is the "IGMP Unsolicited Report Interval". > > Prior to this patch this value was hard coded in the kernel to 10s for > IGMPv2 and 1s for IGMPv3. 10s is unsuitable for some use-cases, such as > IPTV as it can cause channel change to be slow in the presence of packet > loss. > > This patch allows the value to be overridden from userspace for both > IGMPv2 and IGMPv3 such that it can be tuned accoding to the network. > > Tested with Wireshark and a simple program to join a (non-existent) > multicast group. The distribution of timings for the second join differ > based upon setting the procfs knobs. > > igmpvX_unsolicited_report_interval is intended to follow the pattern > established by force_igmp_version, and while a procfs entry has been added > a corresponding sysctl knob has not as it is my understanding that sysctl > is deprecated[1]. > > [1]: http://lwn.net/Articles/247243/ > > Signed-off-by: William Manley Acked-by: Hannes Frederic Sowa